title: A cross-sectional study of the impact of blood selenium on blood and urinary arsenic concentrations in Bangladesh.
abstract: BACKGROUND
  Arsenic can naturally occur in the groundwater without an anthropogenic source of contamination. In Bangladesh over 50 million people are exposed to naturally occurring arsenic concentrations exceeding the World Health Organization's guideline of 10 μg/L. Selenium and arsenic have been shown to facilitate the excretion of each other in bile. Recent evidence suggests that selenium may play a role in arsenic elimination by forming a selenium-arsenic conjugate in the liver before excretion into the bile.
  
  
  METHODS
  A cross-sectional study of 1601 adults and 287 children was conducted to assess the relationship between blood selenium and urinary and blood arsenic in a study population residing in a moderately arsenic-contaminated rural area in Bangladesh.
  
  
  RESULTS
  The results of this study indicate a statistically significant inverse relationship between blood selenium and urinary arsenic concentrations in both adult and pediatric populations in rural Bangladesh after adjustment for age, sex, Body Mass Index, plasma folate and B12 (in children), and ever smoking and current betel nut use (in adults). In addition, there appears to be a statistically significant inverse relationship between blood selenium and blood arsenic in children.
  
  
  CONCLUSIONS
  Our results suggest that selenium is inversely associated with biomarkers of arsenic burden in both adults and children. These findings support the hypothesis that Se facilitates the biliary elimination of As, possibly via the putative formation of a Se-As conjugate using a glutathione complex. However, laboratory based studies are needed to provide further evidence to elucidate the presence of Se-As conjugate and its role in arsenic elimination in humans.
authors.affiliation: Department of International Health, Program in Global Disease Epidemiology and Control, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD E5535, USA. cmgeorge@jhsph.edu
authors.forename: Christine Marie
authors.initials: CM
authors.lastname: George
authors.forename: Mary
authors.initials: M
authors.lastname: Gamble
authors.forename: Vesna
authors.initials: V
authors.lastname: Slavkovich
authors.forename: Diane
authors.initials: D
authors.lastname: Levy
authors.forename: Alauddin
authors.initials: A
authors.lastname: Ahmed
authors.forename: Habibul
authors.initials: H
authors.lastname: Ahsan
authors.forename: Joseph
authors.initials: J
authors.lastname: Graziano
mesh_terms: D000293:Adolescent; D000328:Adult; D001151:Arsenic / Q000097:blood* / Q000652:urine*; D001459:Bangladesh; D015415:Biomarkers / Q000097:blood / Q000652:urine; D002648:Child; D003430:Cross-Sectional Studies; D004781:Environmental Exposure; D004784:Environmental Monitoring; D005260:Female; D006801:Humans; D008297:Male; D013058:Mass Spectrometry; D008875:Middle Aged; D012643:Selenium / Q000097:blood*; D013054:Spectrophotometry, Atomic; D014874:Water Pollutants, Chemical / Q000097:blood* / Q000652:urine*; D055815:Young Adult
chemical_list: D015415:Biomarkers; D014874:Water Pollutants, Chemical; D012643:Selenium; D001151:Arsenic